A nationwide strike has severely crippled schools and public transport across France as workers vent their anger at being forced to retire later or face reduced pensions.
Police, lawyers and hospital and airport staff are joining school and transport workers for a general walkout that could include millions of people.
France’s largest nationwide strike in years was agreed by unions unhappy with President Emmanuel Macron’s plans for a universal points-based pension system.
Authorities have been trying to put in place plans to mediate the disruption.
French newspaper Le Monde described Thursday as “the moment of truth for Macron”, writing: “The next days are a decisive test for the head of state.”
Experts say public transport will be seriously tested, with 90% of high-speed TGV and intercity trains cancelled.
In the capital Paris, just five of the city’s 16 metro lines are running, The BBC writes.
Hundreds of flights have also been cancelled. Air France said it would cancel 30% of internal flights and 30% of short-haul international flights, amid walk-outs by air traffic controllers.
Low-cost carrier EasyJet has cancelled 223 domestic and short-haul international flights, and warned passengers to expect delays.
The industrial action is expected to last beyond Thursday and some trade union leaders have warned they will keep it up until Mr Macron abandons his campaign promise to overhaul the retirement system.